Mine roof supports



0 A. D. ALLEN 3,523,424

MINE ROOF SUPPORTS Filed NOV. 25, 1968 5 Sheets-Sheet 1 INVENTOR:

ARCHELAIUS D. ALLEN Aug. 11, 1970 A. D. ALLEN 3,523,424

MINE ROOF SUPPORTS Filed NOV. 25. 1968 5 Sheets-Sheet 2 A RcHELAius 1 ALLEN INVENTOR:

Aug. 11, 1970 A. D. ALLEN MINE ROOF surroms 5 Sheets-Sheet 5 Filed Nov. 25. 1968 W J H n i lm W m MAT m u ulllmll\w E 2 a 5: Q r M mv\h\ INVENTOR;

M m E & LA L Y A D 5 U 1, 1970 A. b. ALLEN MINE ROOF SUPPORTS 5 Sheets-Sheet 4.

Filed Nov. 25. 1968 INVENTOR:

N a E u L a L A A nwm s o mm .9 0 J A L H A Q f H c R A bw wm. M H mm Q 51 Q %///Z; Q mm mm om A. D. ALLEN 2mm ROOF SUPPORTS Aug. 11, 1970 I 5 Sheets-Sheet 5 Filed Nov. 25, 1968 I l I INVENTOR: D A L L EN A RcHELAius United States Patent Ofice 3,523,424 Patented Aug. 11, 1970 US. Cl. 61-45 8 Claims ABSTRACT OF THE DISCLOSURE A mine roof support comprises a floor-engaging base, hydraulically extensible props mounted on said base, a roof-engaging structure supported on said props for application thereby to a mine roof and a roof-supporting bar extendible and retractable, relatively to said roof-engaging structure, to positions of maximum and minimum extension and to positions therebetween. A pressure-fluid jack is provided between the extendible roof-supporting bar and the base to set said bar against the roof at such position and transmit a load on the roof-supporting bar to said base independently of said hydraulic props of the support. The jack may be pivotally mounted on the support so that the extendible roof-supporting bar can be extended or retracted by adjusting the jack angularly about its pivot and can be set to a mine roof by extending said jack. Angular adjustment of the jack about its pivot may be effected by a pressure-fluid piston and cylinder device.

BACKGROUND OF THE INVENTION In the longwall method of mining, under certain geological roof conditions, thereby is a tendency for material to fall from the unsupported roof between the roof supports and the mineral-bearing face after passage of the cutting or other mineral-winning machine. To minimise this fall of material it is often the practice to provide a roof-supporting bar which is extendible from the main roof-support and which is set immediately after the passage of the cutting machine and prior to the advance of the main support.

The extendible roof-supporting bar is often manually operable. An example of such a manually operable extension bar is described in our British patent specification No. 977,503. Alternatively, the extendible supporting bar may be operated by a ram means as described, for example, in the specification of our British Pat. No. 1,061,071.

Heretofore the return of the extendible, supporting bar to its initial position in the main roof support has been dependent upon the release of the latter from between floor and roof, the load on the extendible bar having made it impossible to, for example, release the wedge or locking means described in specification No. 977,503. Furthermore, it has only been possible to retract the extension bar from its extended position by the operator working over the moving face conveyor. This can be dangerous.

Extendible roof-supporting bar arrangements, as adopted heretofore, have also generally had the disadvantage of adding load to the main roof support because the extended roof-bar increases the area of the roof applied to the support and therefore the total load on the support. The extended roof-bar is also subjected to a tip load which increases the load applied to the forward part of the main support and often causes said support to yield under a reduced total loading.

SUMMARY OF THE INVENTION According to the present invention there is provided a mine roof support comprising a floor-engaging base, hy-

draulically extensible prop means mounted on said base, a roof-supporting member extendible and retractable relaapplication thereby to a mine roof for the support thereof, a roof-supporting member extendible and retractable relatively to said roof-engaging structure to positions of maximum and minimum extension and to positions therebetween, a hydraulic jack, a pivotal mounting on the base of the support for a lower end of said jack, a pivotal connection at an upper end of said jack pivotally connecting it to said extendible and retractable roof-supporting member whereby extension of said jack will set said roof-supporting member to a mine roof for the support thereof, the load on the roof-supporting member being transmitted to the base of the support, by said jack, independently of the hydraulic prop means of the support, and means for adjusting said jack angularly about its pivotal mounting on the base of the support thereby to extend and retract the extensible and retractable roof-supporting member.

Angular adjustment of the jack to advance or retract the extendible roof-supporting member or bar, may be effected manually or by a pressure-fluid piston and cylinder device or ram connected between the jack and the support.

Means may be provided for rendering the extendible roof-supporting bar yielding or nonyielding, e.g. by incorporating a yield valve in the pressure-fluid system of the jack in the manner well known in hydraulic mine roof supports.

The invention will be further described, by way of example, with reference to the accompanying drawings in which:

FIG. 1 is a sectional side elevation of one form of support according to the invenion, the extendible roof-supporting bar being shown in its full retracted position,

FIG. 2 is a sectional side elevation similar to FIG. 1 but with the extendible roof-supporting ban-in an extended position,

FIG. 3 is a plan view of FIG. 1,

FIG. 4 is a sectional side elevation of a further embodiment of the invention, and

FIG. 5 is a plan view of FIG. 4.

The support shown in FIGS. 1, 2 and 3 comprises a base 10 having mounted on it, in the usual way, hydraulically extensible props or legs 11 on which a roof-supporting canopy 13 is mounted also in the usual way. Also mounted on the base 10 is a further pair of hydraulically extensible legs or props 12 which support roof-bars 14 pivotally connected at 15 to the canopy 13.

A hydraulic advancing ram 16 is incorporated in the support and is adapted, as winning of the mineral proceeds, to push the scraper conveyor C towards the newly exposed mineral face and then advance the support up to the conveyor, in the well known way, the ram 16 being connected to the conveyor at 17.

Hingedly mounted on the base 10 by a pivot 22 is a jack or auxiliary hydraulically extensible prop or leg 18 having mounted on it an extendible roof-supporting bar 19, said bar being pivotally connected to the upper part of the prop 18 as indicated at 20. The extendible roof-bar 19 has trunnions 21 which engage slidably with the undersides of the roof-bars or cantilevers 14.

A hydraulic ram 23 has its piston rod connected to the auxiliary prop or ram 18 and 25 and its cylinder connected to the main unit of the support at 24.

To extend or retract the extendible roof-supporting bar 19 pressure-fluid is appropriately applied to one or other side of the piston in the cylinder 23. To set the extendible roof-supporting bar 19 against the roof in any position of extension or retraction pressure-fluid is supplied to the auxiliary prop or ram 18. It will be appreciated that by bleeding-01f or releasing pressure-fluid from the prop 18 the bar 19 can be lowered-off from the roof and retracted either from a fully extended position or from any intermediate position of extension.

The embodiment of the invention shown in FIGS. 4 and 5 is similar in some respects to that already described with reference to FIGS. 1 to 3 and where applicable like reference numerals have been used to designate like parts. In the embodiment shown in FIGS. 4 and 5 however, the roof-engaging structure or canopy 13 is supported on three hydraulic rams or props 26 resiliently mounted in rubber bushes at 27. The extendible roof-supporting bar 19 has a fulcrum 28 at its rear which engages slidably with the underside of the canopy 13 and is guided and accommodated in a recess 32 therein. Extension and retraction of the roof-supporting bar 19 is effected or assisted by a ram 30 supported from the underside of the canopy 13, by brackets 31, and coupled to the roof-supporting bar 19 at 29.

I claim:

1. A mine roof support comprising a floor-engaging base, hydraulically extensible prop means mounted on said base, a roof-engaging structure mounted on said prop means for application thereby to a mine roof for the support thereof, a roof-supporting member extendible and retractable relatively to said roof-engaging structure to positions of maximum and minimum extension and to positions therebetween, a hydraulic jack, a pivotal mounting on the base of the support for a lower end of said jack, a pivotal connection at an upper end of said jack pivotally connecting it to said extendible and retractable roof-supporting member whereby extension of said jack will set said roof-supporting member to a mine roof for the support thereof, the load on the roof-supporting member being transmitted to the base of the support, by said jack, independently of the hydraulic prop means of the support, and means for adjusting said jack angularly about its pivotal mounting on the base of the support thereby to extend and retract the extensible and retractable roofsupporting member.

2. A mine roof support as claimed in claim 1 wherein a pressure-fluid piston and cylinder device is connected 40 between said jack and a relatively fixed part of the support and is operative to adjust said jack angularly about its pivot.

3. A mine roof support as claimed in claim 1 wherein said pressure-fluid jack is connected in a pressure-fluid system which includes a yield valve operative to bleed pressure-fluid from the jack when the roof-supporting member supported thereby is subjected to a predetermined load.

4. A mine roof support as claimed in claim 1 wherein the roof-engaging structure has forwardly projecting roofbar means and the extendible and retractable roof-supporting member has means which engage slidably with the underside of said roof-bar means.

5. A mine roof support as claimed in claim 4 wherein said roof-bar means is pivotally attached to a rearward part of the roof-engaging structure of the support.

6. A mine roof support as claimed in claim 1 wherein the extendible and retractable roof-supporting member has a fulcrum at its rear which engages slidably with the underside of the roof-engaging structure of the support and is guided and accommodated in a recess therein.

7. A mine roof support as claimed in claim 1 wherein extension and retraction of the roof-supporting member is effected by a ram supported from the underside of the roof-engaging structure of the support.

8. A mine roof support as claimed in claim 1 wherein the extendible and retractable roof-supporting member has trunnions which engage slidably with the underside of the roof-engaging structure.

References Cited UNITED STATES PATENTS 3,324,664 6/1967 Allen 6145.2 3,333,426 8/1967 Jackson 6145.2 3,364,683 1/1968 Farr 6145.2 3,370,431 2/1968 Adcock et a]. 61-45.2

FOREIGN PATENTS 1,426,031 12/1965 France. 1,426,731 12/ 1965 France. 1,206,832 12/1965 Germany.

DENNIS L. TAYLOR, Primary Examiner U S. Cl. X.R. 248-357 

